Re: Handling multiple video devices

On Wednesday 07 March 2007 21:13, Anne Wilson wrote:
I have three video devices that may be in use at any time on this box. One
is a pci video-capture card, so always present. The other two are webcam
and usb tv tuner. The problem is that every package that can handle either
the webcam or the tv tuner looks for video0.

tvtime's menu has an entry for changing the input, and I thought that
should do it, but absolutely nothing happens if I click on that. I haven't
had any more luck with amsn + webcam either - as long as it gets video0 it
is happy, but it won't talk to anything else.

There must be some way to configure these to talk to video*. I've had some
luck with getting udev to track the webcam connection, so if I could point
amsn to /dev/webcam, that would be solved. Similarly I could build a rule
for the tuner, but it's no good if I can't get the software to use it.

Has anyone managed this sort of situation?

Anne

Hi Anne. This probably going to be a totally useless reply, but, how are the 3
devices setup at the moment? I think you have Xawtv. Try running xawtv
-hwscan to see how the video devices are setup in /dev.

With xawtv I can specify which device to use when I launch it. For example my
TV tuner card uses /dev/video0, so that is just launched as xawtv. If I want
to use xawtv to access the webcam, I set the command on the desktop launcher
as, xawtv -device /dev/video1, and then get the webcam showing on xawtv. I
don't know much about TVtime, but it may be worth launching it specifying the
device it should use.

Amsn is a problem, as it just looks in /dev/video. If you mess with udev, and
create symlinks (/dev/webcam) Amsn is totally lost. Can't see the wood for
the trees.

My TVtuner card uses /dev/video0, and the webcam (ov511) uses /dev/video1,
except on FC5 with the 2.6.18 kernel, where it's a bit hit and miss in which
order they are loaded. I've used the webcam using /dev/video1 while talking
to you on Amsn, so I don't think there is a problem with Amsn, as long as it
can find a webcam device in /dev/video, whether that's /dev/video0, 1, 2, or
3.

I don't if this is any help, but on FC2 the USB webcam was being
given /dev/video0, and the TVtuner card wasn't being loaded. The TVtuner card
should be loaded as /dev/video0, and the webcam as /dev/video1, but that was
an FC2 problem. USB starts early in the boot process, and USB devices were
loaded before PCI stuff.

This is what I did on FC2 in /etc/rc.d/rc.local to fix it.

/sbin/modprobe -r ov511 (remove webcam using /dev/video0)

/sbin/modprobe tda9887 port2=0 pal=I (load TVtuner card to /dev/video0)
/sbin/modprobe bttv tuner=38 automute=0 (more TVcard stuff)
#install bttv /sbin/modprobe tda9887 port2=0 pal=I; /sbin/modprobe
--ignore-install bttv

/sbin/modprobe ov511 force-palette=15 (load webcam to /dev/video1)

It may be worth trying something like this. I don't think there is a problem
with the webcam, so that can be loaded last, as Amsn is just looking
in /dev/video for a webcam device. The TVtuner card I don't know about, but
may be worth loading this first so that it grabs /dev/video0, especially as
you have problems with TVtime. Load the driver for the PCI video-capture card
second, and the driver for the webcam third.

If all 3 drivers are already loaded you will have to do a modprobe -r for each
one in /etc/rc.d/rc.local before modprobing them in the order you want to
have them loaded.

Personally I think this is a bit of a hack, but it has worked to get the
TVtuner card, and the webcam driver loaded in the correct order on FC2.

All the best.

Nigel.









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